In the macaque monkey more than half of the cerebral cortex is involved in processing visual information. In addition to the striate cortex (VI) eight extrastriate visual areas have been identified to date. The first goal of the present proposal is to determine the full extent and topographic organization of several of these areas, including V3, V4 and two newly identified areas along the juncture of the occipital and temporal lobes. Our approach will be to examine cortical myeloarchitecture in conjunction with physiological and anatomical mapping of visual topography. A second goal is to identify the major inputs and outputs of these and other visual areas using a combination of anterograde and retrograde tracing techniques. Knowledge of these pathways will help clarify important hierarchical relationships between visual areas. Our third major goal is to determine the functional properties of cells in several visual areas, including V4 and the Middle Temporal area (MT). Most cells in MT have a strong preference for visual stimuli moving in particular directions. We will test whether cells having similar direction preferences are organized into orderly columnar groupings by making multiple, closely spaced microelectrode penetrations and by using 2-deoxyglucose method to map functionally active regions of cortex. The extent to which MT is involved in analyzing movement in three-dimensional space will be investigated. By comparing the properties of cell in different cortical layers it may be possible to establish what types of information processing take place within MT. Functional studies on V4 will concentrate on its role in the analysis of color, because it contains many color-specific cells. As with MT, we will examine the laminar and columnar distribution of different cell types in V4. Receptive fields in V4 will be compared with those in a newly identified area in ventral occipital cortex which also receives inputs from V2 but not Vl. The overall results of the proposed research may yield new insights into the organization and function of higher visual areas in primates.